Tackling the outbreak of nipah virus in Bangladesh amidst COVID‐19: A potential threat to public health and actionable measures

on scatteredly reported nipah virus with utmost importance before it becomes a major health burden.

Tackling the outbreak of nipah virus in Bangladesh amidst COVID-19: A potential threat to public health and actionable measures Nipah virus of family paramyxovirus is a highly virulent infectious pathogen with epidemic potential. 1Nipah virus is a zoonotic (pig, cattle), mainly a bat-borne (Pteropus) 1,2 pathogen reported in South to Southeast Asia [1][2][3][4] that can be transmitted between humans.2][3][4][5] With no effective treatment or vaccines and a case fatality rate of about 75%, the World Health Organization (WHO) has defined nipah virus as priority pathogen with a high risk of epidemic potential. 4,54][5] The effective intervention to contain larger outbreaks requires an understanding of the mechanism of breaching of virus host barrier and transmission to human.
Nipah virus was first identified in Malaysia during 1998−1999. 5,64][5][6] Due to the abundance of known reservoir of nipah virus, the countries in Southeast Asia including India, Bangladesh, Myanmar, Cambodia, Ghana, Indonesia, Madagascar, the Philippines, and Thailand are at high risk of outbreaks. 5,6[7] The highest number of cases (67) were reported in 2004, followed by 43 in 2011, 37 in 2014, 31 in 2013, 18 in 2007 and 2010, 17 in 2012, and 15 in 2015, respectively (Figure 1). 7,86][7][8] The actual burden of nipah virus is significantly higher than the reported cases and fatalities in Bangladesh due to lack of real-time and sensitive countrywide surveillance.
The first case was documented from Meherpur, 4 the northwestern district in Bangladesh during 2001.Out of 64 districts, sporadic cases have been found in 32 districts (50%). 5,8The highest number of cases (67 and 43 confirmed cases) and fatalities (50 and 37) was reported from Faridpur, a central district in 2004 and 2011, respectively (Supporting Information S1: Figure I). 7,8About 21−30 confirmed cases from Lalmonirhat, Naogaon, (the northern districts), and Rajbari were reported individually.Confirmed cases were found mostly from the central and northern districts in Bangladesh. 7,8The first identified probable risk factor was close contact with sick cow in Meherpur in 2001 followed by probable person-to-person transmission. 1,4,7After that, close contact with pig herds, climbing trees contaminated with feces of bats followed by human-to-human transmission were detected as source of infection in 2003 in Naogaon and 2004 in Rajbari, respectively.The largest outbreak in Faridpur in 2004 was started from probably drinking raw date sap and contaminated droplets or fomites from infected persons. 1,4,7,8inking raw date palm sap contaminated with bat droppings or saliva was first identified as probable source of nipah virus in 2005 in Tangail. 4 Among 333 cases, 223 (68%) were infected from spillover, animals, or unidentified source and 110 (32%) were infected from person-to-person. 1,4,7,8However, both the sources of unreported and reported cases require more specific investigation to accurately identify the risk factors.
The limited epidemiological survey documented that nipah virus infection are most prevalent in male (~65%) 1 and about 40% of the cases are reported among patients aged ≤18 years in Bangladesh. 1,7out 90% case patients required hospitalization and 60% died before 7 days from the onset of the symptoms. 1Among the clinical manifestations, fever (100%) is the most common followed by altered mental status 85%, sever weakness (72%), difficulty in breathing (64%), vomiting (55%), and cough (52%), respectively. 1,3The high case fatality rate, continuous outbreaks, and seasonal sporadic cases and the lack of adequate knowledge of the sources of the transmission requires urgent attention to avoid future health crisis.
The first case of COVID-19 pandemic was documented on March 8, 2020 in Bangladesh. 9About two million cases and 30,000 deaths are reported from Bangladesh during 2020 and 2023. 9During the pandemic like most other countries, the health sector in Bangladesh was significantly affected.Majority of the efforts, strategies, and dedication were given for the prevention and management of COVID-19 cases. 10Thus, the pandemic has contributed to a significant lack in the healthcare facilities. 10 Climate changes may also have direct impact on the seasonal outbreaks of nipah virus in Bangladesh.One of the well identified sources of transmission of nipah virus is contaminated date sap, that becomes available in winter (December to February) in Bangladesh.
As a traditional drink, many people in rural areas take raw date sap contaminated with bat spill-over or saliva and get infected by nipah virus (Supporting Information S1: Figure II).
The national surveillance of nipah virus is not strong and available in only limited number of hospitals covering small regions in Bangladesh.Furthermore, the health system is not sufficiently designed to conduct operational surveillance across the country.Moreover, genomic surveillance data are insufficient to understand the evolutionary dynamics in Bangladesh.Globally, there is no approved treatment or vaccine against nipah virus.
Preventive measures include policy of reduced exposure to infected bat, animal, and human to minimize transmission.Some local preventive measures such as using protection of cloth net in the clay pot during overnight date sap collection may reduce contamination by bat saliva or spill-over.Further, programs to build public awareness to avoid drinking raw date sap must be undertaken regularly countrywide.
We have identified three major gaps related with public health concern of nipah virus outbreak in Bangladesh.First, cases of nipah virus with 72% case fatality rate is occurring every year in Bangladesh; second, lack of a strong countrywide surveillance and management system dedicated to nipah virus outbreak and insufficient genetic characterization; third, lack of regular campaign on building awareness about preventive measures among general people, specifically training of raw date sap collectors to use protection during overnight collection and lack of emergency response health facilities to tackle a larger outbreak and reduce health burden.In conclusion, the authorities should take integrated public health measures and emphasize on scatteredly reported nipah virus with utmost importance before it becomes a major health burden.

KEYWORDS
annual outbreaks, Bangladesh, fruit bat, nipah virus, risk factors As a result, cases of nipah virus, WHO defined priority pathogen, received lack of priority and underreporting due to diversion of health facilities towards COVID-19.Further, the significant proportion of overlapping symptoms of nipah virus and COVID-19 infection has made it difficult to conduct differential diagnostic during the pandemic.The emergency situation during the COVID-19 pandemic also made it difficult to identify any coinfection by both nipah and COVID-19.